从正弦激励下线性二阶系统的微分方程出发，结合阻尼振子的受迫振动以及RLC 串联、并联谐振电路等具体物理情境，剖析了品质因数Q 在频率特性、能量转换以及系统各物理参数等多个层次上的内涵，进而探讨如何更好地为工科各专业学生讲授品质因数这一概念.

Multiple connotations of the quality factor Q associated with frequency characteristic，energy conversion，and various physical variables are analyzed. The analysis is based on the differential equation of second-order system with sinusoidal excitation，as well as the physical contexts of forced damping vibration and RLC serial /parallel resonant circuits. Then it is also discussed that how to teach the concept of quality factor Q better for engineering students.